Question

A galvanometer gives full scale deflection with 0.2 A in its coil. The resistance of its coil is 10 $\Omega$. How much shunt resistance is required to convert it into an ammeter to read current upto $1.8$ A?

• A. 5.0 $\Omega$
• B. 2.5 $\Omega$
• C. 1.25 $\Omega$
• D. 10.0 $\Omega$

Answer 1

The correct option is B 2.5 $\Omega$

$\begin{array}{c}0.2\times 10=\left(1.8-0.2\right)R\\ \Rightarrow 2=1.6R\\ \therefore R=\frac{20}{16}=\frac{5}{4}\\ =1.25\Omega \end{array}$

$\therefore$ Option $C$ is correct.